Folding doors according to the preamble are known from WO 2008/125343 A1 of the same applicant and from the International Patent Application PCT/EP2012/000157 of the applicant of Jan. 16, 2012, whose content is included here by reference in the present patent application. According to WO 2008/125343 A1, adjustment sections are needed during the installation of the folding shutter in or in front of a building opening. There are no possibilities for sealing the closed folding door on the margin. All of these documents are incorporated by reference into the specification of this application.